Semiconductor processing in the fabrication of integrated circuitry typically includes the deposition of layers on semiconductor substrates. Exemplary processes include physical vapor deposition (PVD) and chemical vapor deposition (CVD). In the context of this document, “CVD” includes any process, whether existing or yet-to-be developed, where one or more vaporized chemicals is fed as a deposition precursor for reaction and adherence to a substrate surface. By way of example only, one such CVD process includes atomic layer deposition (ALD). With typical ALD, successive mono-atomic layers are adsorbed to a substrate and/or reacted with the outer layer on the substrate, typically by successive feeding of different precursors to the substrate surface.
Chemical vapor depositions can be conducted within chambers or reactors which retain a single substrate upon a wafer holder or susceptor. One or more precursor gasses are typically provided to a shower head within the chamber which is intended to uniformly provide the reactant gasses substantially homogeneously over the outer surface of the substrate. The precursors react or otherwise manifest in a deposition of a suitable layer atop the substrate. Plasma enhancement may or may not be utilized, and either directly within the chamber or remotely therefrom.
In certain chemical vapor deposition processes, including ALD, precursors are pulsed or otherwise intermittently injected into the reactor for reaction and/or deposition onto a substrate. In many cases, it is highly desirable to turn the individual precursor flows on and off very quickly. For example, some deposition processes utilize plasma generation of a precursor in a chamber remote from the deposition chamber. As the precursor leaves the remote plasma generation chamber, such typically converts to a short lived, non-plasma desired active state intended to be maintained for reaction in the deposition chamber. Yet plasma generation in the remote chamber is very pressure dependent, and the plasma typically ceases in the remote chamber when switching/pulsing the active species flow to the chamber. Accordingly, such process are expected to utilize pulsed remote plasma generation, and which may not be practical.
The invention was motivated in overcoming the above-described drawbacks, although it is in no way so limited. The invention is only limited by the accompanying claims as literally worded without interpretative or other limiting reference to the specification or drawings, and in accordance with the doctrine of equivalents.